1. Field of the Invention
The invention relates to the field of bicycles driven by shafts and, more particularly, to the field of one and two-wheel drive bicycles having one or both of the front wheel and the rear wheel driven by a series of shafts that are themselves coupled to a transmission having a plurality of ring gears.
2. Description of the Prior Art
Two-wheel drive bicycles are known in the art and generally comprise either a shaft drive, a chain or belt drive, a cable drive or some combination thereof. For example, U.S. Pat. No. 4,479,660 (Pattison) describes an endless belt drive system for the front wheel that is driven by the bicycle pedals. In a somewhat similar vein, U.S. Pat. No. 4,773,662 (Phillips) describes a second chain drive system for the front wheel that is driven by an auxiliary hand crank. A cable drive system, on the other hand, is described in U.S. Pat. No. 5,052,705 (Ringle). Instead of being driven by the bicycle pedals or an auxiliary hand crank, the Ringle cable drive is driven by the rotation of the rear wheel, which is itself driven in standard fashion by the bicycle pedals. A similar cable drive is described in U.S. Pat. No. 5,184,838 (Becoat). A combination of chain drives and shafts is described in U.S. Pat. No. 5,158,314 (Farras Pinos). In a manner similar to the Ringle cable drive, the Farras Pinos combination drive is driven by the rotation of the rear wheel. A similar combination of chain drives, cable drives and/or flexible shafts is described in U.S. Pat. No. 5,224,725 (Erlston) and in U.S. Pat. No. 5,332,244 (Turner et al.). Other combinations of drive mechanisms are described in, for example, U.S. Pat. No. 6,095,540 (Kim), U.S. Pat. No. 6,161,854 (Christini et al.), U.S. Pat. No. 6,406,047 (Sawyer, Jr.) and U.S. Pat. No. 6,419,255 (Chang et al.).
A two-wheel drive bicycle includes a main frame having a steering head, a seat tube, a cross bar and a hollow downtube. A main drive mechanism includes a housing, a driving spindle, at least one driven ring gear, a first driven shaft and a second driven shaft. The housing is connected to the main frame while the driving spindle is rotatably connected to the housing as well as to the pedals of the bicycle. The first driven shaft is rotatably connected to the housing and operably coupled to the at least one driven ring gear. The second driven shaft is, likewise, rotatably connected to the housing and operably coupled to the at least one driven ring gear.
A front wheel drive mechanism includes a first shaft means rotatably positioned inside of the hollow downtube and a second shaft means rotatably positioned inside of a hollow fork tube. The first shaft means has a first end operably coupled to the first driven shaft and a second end operably coupled to the second shaft means. The second shaft means is operably connected to the front wheel. A rear wheel drive mechanism includes a third shaft means rotatably positioned inside of a hollow chain stay. The third shaft means has a first end operably coupled to said second driven shaft and a second end operably coupled to the rear wheel.
The main drive mechanism preferably includes a plurality of driven gears comprising a series of concentrically spaced ring gears. Each ring gear of the plurality of driven ring gears has an inner diametrical surface and an outer diametrical surface. Each outer diametrical surface is configured to engage the inner diametrical surface of an adjacent ring gear. Further, the main drive mechanism preferably includes a biasing means for biasing each ring gear away from the first driven shaft and the second driven shaft and a selective engagement means for selectively engaging one ring gear of the plurality of ring gears with the first driven shaft and the second driven shaft. A shifter mechanism operates the selective engagement means and a user propels the bicycle using a standard pair of bicycle pedals.
Other embodiments of the present invention are contemplated and include use of the main drive mechanism to propel either the front wheel or the rear wheel in a single wheel drive embodiment or to propel both wheels in a two wheel drive or dual wheel drive embodiment. Shock absorbing elements for the front and rear wheels, separately or together, are also contemplated for use with both the single and dual wheel embodiments. Each of the components that make up the contemplated embodiments, moreover, are constructed using standard materials typically used for constructing bicycle frames and components, such as, for example, aluminum, steel or titanium. Alternatively, the components may be constructed using fiber reinforced plastics, which offer superb strength to weigh ratios when compared to other materials.